Double-acting bellows pump



July 5, 1955 l.. c. HARDlsoN 3,192,860

DOUBLE-ACTING BELLOWS PUMP Filed oct. 2e, 19ers :e sheets-sheet 1 Las/l'e C. Hard/'san TTR EYS L. C. HARDISON DOUBLE-ACTING BELLOWS PUMP July 6, 1965 2 SheetsfSheet 2.

Filed Oct. 28, 1963 Figure 3 F l'gure 4 /V VEN TOR: Les/ie 6. Hard/'son BY:

A TTOR/VEYS 3,192,860 DOUBLE-ACTING BELLOWS PUNIP -Leslie C. Hardison, Arlington Heights, Ill., assigner to Universal @il Products Company, Des Plaines, Ill., a corporation of Delaware Y Filed Oct. 23, 1963, Ser. N 319,393 7 Claims. (Cl. 10S- 44) This invention relates to an improved bellows pump for pumping liquids or gases at a precise and positive rate without substantial pulsations or interruptions in the ow rate. Y

Pumping apparatus of the surge type, exempliiied by diaphragm and bellows pumps, nds application whenever it is necessary or desirable that the process fluid be isolated from contact with Ythe piston, rotor or other uid impelling means coupled to a rotary or reciprocating drive shaft through shaft seal means. It is also useful for pumping iluids at very low flow rates as in bench-scale, semi-works and pilot plant process units. A typical bellows pump construction is described in U.S.

`Patent 2,735,369. One drawback with thisand lother United States Patent O surge pumps of the prior art is that pressure and/ or ilow therefrom, being particularly troublesome in small scale units' where ow rates are low and time constants and transport lags are large.

The present invention combines the advantages of a surge pump with those of a continuous pump of the centrifugal or rotary type. Process uid isolation and precisely controlled flow rates are achieved, and the iiow is practically free of pulsations. 'Ihe invention includes two bellows members, each disposed in a separate bellows chamber, and a bidirectional or reversible positive displacement pump. The bidirectional positive displacement pump has a pair of ports which alternately serve as suction and discharge ports. Each of the bellows members is connected in sealed uid communication with a corresponding one of these two ports, and both bellows members and the pump are lilled with a suitable hydraulic liquid to form a liquid-lilled system. As above noted,- a fluid-tight chamber or housing surrounds each of the two bellows members. Suction and discharge lines containing unidirectional ow conducting valves admit suction iluid to one chamber while permitting discharge iluid to be pressured out of the other chamber. The positive displacement pump is initially driven in one direction, causing hydraulic liquid to be withdrawn from one bellows and forced into -the other. The one bellows contracts, whereby its surrounding housing becomes lled with suction side process Huid, and the other bellows expands to discharge process uid previously admitted to its chamber. After a predetermined volume of hydraulic liquid has been displaced from one bellows to the other, ythe positive displacement pump is reversed with respect to its driving direction and the hydraulic uid is pumped from the now expanded bellows back to the now contracted bellows. The bellows chamber which previously served as a suction fluid reservoir now becomes the discharge cylinder, and the bellows chamber which previously served as the discharge cylinder now becomes the suction uid reservoir. Means are provided for periodically reversing the driving direction of the positive displacement pumping means so that essentially continuous ow of the process iluid is maintained.

The structure and operation of this invention Ais described below in conjunction with the accompanying drawings which are presented as illustrative of theV bestY c ICC` mode of constructing and practicing the invention but not with the intention of unduly limiting its broad scope. Obvious modifications and substitution of equivalents in the specific apparatus illustrated will be readily apparent to those skilled in the art.V

FIGURE 1 is a sectional schematic view of the pumping apparatus.

FIGURE 2 is a block diagram of suitable driving, reversing-and reversing control apparatus.

FIGURES 3 and 4 illustrate in greater detail one form of reversing apparatuswhich may be employed.

In FIGURE 1 there is indicated Va rotary gear pump casing 1 within whichv enmeshng spur gearY members 2 and 3 `are rotatably mounted, their teeth in snug sliding contact with the curved wall portions of casing 1 to define a conventional positive displacement rotary gear pump. Ports 4 and 5 are, respectively, the suction and discharge ports for clockwise rotation of gear 2, and the discharge and suction ports for counterclockwise rotation of gear 2. Bellows housings or chambers 6 and 8 are attached to opposite faces of casing 1; these chambers are imperforate, (except for passageways 20, 21) and duid-tight. Mounted within chamber 6 is a first resilient bellows member 7. The free end of bellows 7 is capped or otherwise sealed; the xed end of bellows 7 is open -to provide uid communication from the bellows interior to port 4, but the peripheral edge of said xed end is sealably secured, as by welding, brazing, clamping or bolting, to casing 1. Radial clearance between the longitudinal wall of bellows 7 and the longitudinal wall of casing 6 is preferably kept to a minimum, but not so close that the bellows will bind in its fully compressed position, so that chamber 6 may provide some measure of support and alignment for the A second resilient bellows member 9 is Hydraulic fluid tills bellows 7 and 9, as Well as ports 4 and 5 and the internal passages of casing 1. The hydraulic fluid may be any suitable liquid such as water, alcohol, glycerine, mercury or a hydrocarbon; a preferred hydraulic liquid is a heavy hydrocarbon oilof substantial Vviscosity and good chemical stability with respect to oxidative and thermal effects, such as is employed in hydraulic power transmission systems. A gear pump handling a viscous, clean, gas-free oil provides an extremely stable ow rate with essentially no spillback and wide rangeability of ilow as a function of speed.

A process iluid suction header 11 is connected by parallel Isuction lines 12 and 16, through passageways 20 and 21, to chambers 6 and 8 respectively. Line 12 contains a ball che-ck valveV 13 and line 16 contains a ball check valve 17.

Check valves 13 `and 17 are poled to admit process ilud from header 11 into chambers 6 and 8 Iand to block flow in the opposite direction. A process tluid discharge header 22 is connected by parallel discharge Ilines 14 and 18, through passageways 2li and 21, to chambers 6 and 8 re- Vspectively. Line 14 contains -a ball check valve 15 and line 1S contains a Vball check valve 19. `Check valves 15 and 19 are poled t-o pass process fluid from chambers 6 and S t0 header 22 and to block ow in the opposite direction.

With the gear pump being driven in the `direct-ion indicated in FIGURE l (gear 2 clockwise and gear-3 counterclockwise), hydraulic liquid is pumped from bellows 7 into bellows 9. Bellows 7 continuously contracts .and the increasing kvolume of chamber 6 is filled with process iluid from header 11 vialine 12-valve 13-passageway 26.

YMeanwhile Vbellows 9 continuously expands, forcing the process fluid previously stored in chamber 8 to discharge via passageway 21-valve 19-line 18 to header 22.

VValves l15 and 17 are closed at -this time by virtue of the pressure differential thereacross. The gear pump is driven in this direction until a predetermined volume of hydraulic fluid is displaced from bellows 7 into bellows 9. Such volume is selected `so that neither bellows is overstressed, whether by reason of overcompression, overex-tension or Contact between the free end of a bellows and the adjacent end wall of its chamber. When bellows 9 reaches its maximum distended position, the driving direction of the gear pump is reversed (gear 2 couuterclockwise and gear 3 clockwise). Now `hydraulic: liquid is pumped from bellows 9 into bellows '7. Bellows 9 continuously contracts and the increasing volume of chamber 8 is filled with process fluid from header 1l via line :i6-valve l7-'passageway 2l. Meanwhile bellows 7 continuously expands, forcing the process iiuid previously stored in chamber 6 to diS- charge via passageway Ztl-valve lS-line 14`to yheader22. Valves i3 and i9 are closed at this time by virtue of the pressure diiierential thereacross. When bellows 7 reaches its maximum distended position, the driving'direction of the gear pump is again reversed and the above described pumping mechanism continues. It is seen therefore that the hydraulic liquid is pumped back and forth from one bellows to the other, causing process iiuid to be continually displaced from the suction side of the discharge side. VOperation on an essentially constant flow basis is readily lobtained by pumping in each direction for a -t-ime interval long in comparison to the time required for reversal of the pump. Whereas the output pressure vs. time curve of surgeY pumps of the prior art is characterized by closely spaced pressure peaks, the output curve of the present pump is characterized by'widely spaced peaks with the interval therebetween being defined by an essentially straight line.

The block diagram of FIGURE 2 depicts a combination of elements for driving and reversing the rotary gear pump of FIGURE l. An electric motor 31 is coupled to a variable speed reducing means 33 by shaft 32. Speed reducer 33 is coupled to a reversing gear mechanism 35 by a Ilow speed shaft 3K5. A revolutioncounter 35, connected to shaft 34, is arranged to trip'electric switch contacts 37 after a predetermined but vadjustable number of revolu- .tions,.or `fractional' part of lone revolution, of shaft 34.

Contacts 37 impose a voltage across lead Wires 33 (shown Vvhere for convenience as a single line) suitable for actuating a solenoid associated with means 35. Alternatively, counter 35 may be replaced with a digital tachometer, the pulse `train output of which is fed to a time gate counter or frequency divider which produces alternate and l output signals each corresponding to a given number of input pulses. Alternatively, purely mechanical control means, or pneumatic or Ihydraulic control means may be employed for generating a reversin-g signal, as will be obvious to thoserskilled in the art; In still another but less desirable embodiment, positive feed forward from shaft 34 to reversing means 36 may be omitted, andthe reversing signal may instead be derived from a clock timer which may be manually synchronized with speed reducer 33.

FIGURES 3 and 4 illustrate one appropriate type of reversing gear assembly, indicated generally by numeral 36 in FIGURES 2 and 3. FIGURE 4 is an end View of the assembly taken along line 4-4 of FIGURE 3. Correspondence between certain of the elements shown here with those of FIGURES l and 2 is indicated by use of the same identifying numeral. Pumping gears 2 and 3 appear in side view within casing 1. Gear 2 is driven by shaft 42 which is supported by a sleeve bearing 43 and sealed by sha-ft seal 4d. Gear 3 is driven by shaft 46 which is sup- `ported by la sleeve bearing 47 sealed by shaft seal 4S.

Shafts 42 and 46 are keyed respectively to external d-rivc gears 4i and 45. A main drivegear 49 is keyed to low speed drive shaft 34. A reversing idler gear 5t), rotatably mounted on a translatable shaft 51, can occupy either an upper or a lower position. Solenoid 52 is coupled to shaft 51 by a connecting rod Srl. Upon energization of solenoid 52, idler gear 50 is withdrawn to its lower position. Upon de-energization of solenoid Y52, compression spring 53 forces rod 54 upwardly to return idler gear 50 to its upper position. In its upper position idler gear Si) transmits power from gear 49 t-o gear 4l, whereby pumping gear 2 is driven and pumping gear 3 is idling. In its lower positi-on idler gear Sil transmits power from gear 49 to gear 45, whereby pumping gear 3 is driven and pumping gear 2 is idling.

Materials of construction will be selected in accordance with operating pressure, temperature and the chemical nature of the process fluid being pumped. Since the bellows members are subject to very little differential pressure, they may be fabricated of suitably thin metal, for example, phosphor bronze, brass or stainless steel7 with foremost regard in the design lthereof being given to meeting extensibility specifications.

The rota-ry gear pump may be of any suitable deslgu and instead of spur gears it may use herringbone gears, Vhelical gears ora combination of these. Other types of bidirectional positive displacement pumps which may be employed in the present invention -include lobe pumps, :screw pumps, vane pumps, cam pumps, and reciprocating -piston pumps. The driving and reversing means will, of course, be designed to match the particular pumping means utilized.

It .isnot essential that thebellows and bellows chambers be integrally mounted on the positive displacement pumping means. The chambers may be individual vessels separated from the pump with the bellows members being connected to the pump `by conduit means. The check valves may be replaced with automatically actuated gate valves or butterfly valves, a variation which will prove advantageous when the process liuid contains inely divided solid-s which might plug or erode the check valves.

Preferably both bellows members and both bellows chambers-should be of equal volume so that a given number of shaft revolutions in either direction will correspond to the same volumetric displacement of hydraulic liquid; if such .equality is not provided, the number of reversals for a given process iiuid throughput will be increased, as fixed by the chamber of smaller volume.

The bellows pump of this invention can handle not only .liquids and gases but such dimculty pumpable process liuids as slurries and gas-solids suspensions. In all cases :an extremely precise, widely adjustable flow rate is attained Without substantial pressure pulsations or interruptions iu li-ow.

I claim as my invention:

1. A liuid pump comprising:

(l) A pair of fluid-tight chambers;

(2) a resilientbellowsmember mounted within each of said chambers, said bellows member being free to expand and contract within its chamber and the interior thereof .being sealed from the interior of ythe chamber;

(3) a bidirectional positive displacement pumping means;

(4) means providing fluid communication from the interior of one bellows member through said pumping means to the interior of the other bellows mem- Vber; (5) a body of liquid illing said bellows membersY and said pumping means; (6) first and second valved suction conduits separately connecting with said chambers; (7) first and second valved discharge conduits separately connecting with said chambers; (8) Vmeans for driving said pumping means in both forward and reverse directions; and (9) means for periodically reversing the driving direction of said pumping means in response to a predetermined displacement'of said pumping means in Y each direction. 2.' The fluid pump of claim l further characterized in the provision of a common suction .header and a common discharge header, said suction conduits connecting said chambers to the suction header and said discharge condui-ts connecting vsaid ychambers to the discharge header.

3. A iluid pump comprising: (1) a pair of duid-tight chambers; (2) a resilient bellows member mounted within each of said chambers,A said bellows member being free to expand and contract within its chamber and the interior thereof being sealed from the interior of theY chamber;

(3) a bidirection rotary gear pumping means;

(4) means providing uid communication froml the interior of one bellows members through said pumping means to the interior of the other bellows member;

(5) a body of liquid lling said bellows members and said pumping means;

(6) irst and second check-valved suction conduits separately connecting with said chambers;

(7) rst and secondcheck-valved discharge conduits separately connecting with said chambers;

(8) means for driving said pumping means in both clockwise and counterclockwise directions; and

(9) means for periodically reversing the driving direction of said pumping means in response to a predetermined displacement of said pumping means in sponse to a predetermined angular displacement of the (5) a body of liquid iilling said bellows members and said pumping means; Y (6) first and second valved suction conduits separately connecting with said chambers; (7 first and second valved discharge conduits separately connecting with said chambers;

(8) means for driving said pumping means in both Y forward and reverse directions; and Y (9) means for periodically reversing the driving direction of said pumping means in response to a predetermined displacement of said pumping means in each direction. Y

References Cited by the Examiner Y UNITED STATES PATENTS 862,867l s/o? Eggleston 23o-17o Y 1,429,101 9/22 Ross V V 6052 1,446,366 2/23 Young 10s- 3.V

FOREIGN PATENTS 1,050,200 2/59 Germany.

ROBERT MQWALKER, Primary Examiner. 

1. A FLUID PUMP COMPRISING: (1) A PAIR OF FLUID-TIGHT CHAMBERS; (2) A RESILIENT BELLOWS MEMBER MOUNTED WITHIN EACH OF SAID CHAMBERS, SAID BELLOWS MEMBER BEING FREE TO EXPAND AND CONTRACT WITHIN ITS CHAMBER AND THE INTERIOR THEREOF BEING SEALED FROM THE THE INTERIOR OF THE CHAMBER; (3) A BIDIRECTIONAL POSITIVE DISPLACEMENT PUMPING MEANS; (4) MEANS PROVIDING FLUID COMMUNICATION FROM THE INTERIOR OF ONE BELLOWS MEMBER THROUGH SAID PUMPING MEANS TO THE INTERIOR OF THE OTHER BELLOWS MEMBER; (5) A BODY OF LIQUID FILLING SAID BELLOWS MEMBERS AND SAID PUMPING MEANS; (6) FIRST AND SECOND VALVED SUCTION CONDUITS SEPARATELY CONNECTING WITH SAID CHAMBERS; (7) FIRST AND SECOND VALVED DISCHARGE CONDUITS SEPARATELY CONNECTING WITH SAID CHAMBERS; (8) MEANS FOR DRIVING SAID PUMPING MEANS IN BOTH FORWARD AND REVERSE DIRECTIONS; AND (9) MEANS FOR PERIODICALLY REVERSING THE DRIVING DIRECTION OF SAID PUMPING MEANS IN RESPONSE TO A PREDETERMINED DISPLACEMENT OF SAID PUMPING MEANS IN EACH DIRECTION. 